Formulation and implementation of optimal control strategies for variable waveshape drives
Abstract
This work investigates optimal current control in two key variable waveshape drive systems—non-sinusoidal permanent-magnet synchronous machine (PMSM) and switched reluctance machine (SRM) drives. For the PMSM case, closed-form methods of optimizing the phase current waveform for minimum rms current and torque ripple are given. Optimization for the SRM drive is also carried out, but in numerical fashion. In both cases, however, the optimized waveforms contain significant harmonics that must be precisely obtained in practice for true optimal efficiency and minimum torque ripple. Conventional modulation techniques do not ensure precise realization of non-sinusoidal current commands. This work sets forth a multiple reference frame based synchronous regulator that allows currents of arbitrary waveshape to be precisely achieved thereby providing a means to achieve true optimum efficiency and minimum current ripple. The proposed control for the PMSM and SRM is verified in simulation and experimentally. The regulator has several other potential applications including induction motor drives and power supplies.
Degree
Ph.D.
Advisors
Sudhoff, Purdue University.
Subject Area
Electrical engineering
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